Preparation and electrochemical performance of SnO_2@carbon nanotube core-shell structure composites as anode material for lithium-ion batteries

摘要

Carbon nanotube-encapsulated SnO_2 (SnO_2@CNT) core-shell composite anode materials are prepared by chemical activation of carbon nanotubes (CNTs) and wet chemical filling. The results of X-ray diffraction and transmission electron microscopy measurements indicate that SnO_2 is filled into the interior hollow core of CNTs and exists as small nanoparticles with diameter of about 6 nm. The SnO_2@CNT composites exhibit enhanced electrochemical performance at various current densities when used as the anode material for lithium-ion batteries. At 0.2 mA cm~(-2) (0.1C), the sample containing wt. 65% of SnO_2 displays a reversible specific capacity of 829.5 mAh g~(-1) and maintains 627.8 mAh g~(-1) after 50 cycles. When the current density is 1.0, 2.0, and 4.0 mA cm~(-2) (about 0.5, 1.0, and 2.0C), the composite electrode still exhibits capacity retention of 563, 507 and 380 mAh g~(-1), respectively. The capacity retention of our SnO_2@CNT composites is much higher than previously reported values for a SnO_2/CNT composite with the same filling yield. The excellent lithium storage and rate capacity performance of SnO_2@CNT core-shell composites make it a promising anode material for lithium-ion batteries.